<!DOCTYPE html>

<html>

<head>
    <title></title>
    <script src='../vue.js'></script>
</head>

<body>
    <div id="watch-example">
        <p>
            Ask a yes/no question:
            <input v-model="question">
        </p>
        <p>{{answer}}</p>
    </div>
    <!-- Since there is already a rich ecosystem of ajax libraries    -->
    <!-- and collections of general-purpose utility methods, Vue core -->
    <!-- is able to remain small by not reinventing them. This also   -->
    <!-- gives you the freedom to just use what you're familiar with. -->
    <script src="https://unpkg.com/axios@0.12.0/dist/axios.min.js"></script>
    <script src="https://unpkg.com/lodash@4.13.1/lodash.min.js"></script>
    <script>
        var watchExampleVM = new Vue({
            el: '#watch-example',
            data: {
                question: '',
                answer: 'I cannot give you an answer until you ask a question!'
            },
            watch: {
                // 如果 question 发生改变，这个函数就会运行
                question: function (newQuestion) {
                    this.answer = 'Waiting for you to stop typing...';
                    this.getAnswer();
                }
            },
            methods: {
                // _.debounce 是一个通过 lodash 限制操作频率的函数。
                // 在这个例子中，我们希望限制访问yesno.wtf/api的频率
                // ajax请求直到用户输入完毕才会发出
                // 学习更多关于 _.debounce function (and its cousin
                // _.throttle), 参考: https://lodash.com/docs#debounce
                getAnswer: _.debounce(
                    function () {
                        if (this.question.indexOf('?') === -1) {
                            this.answer = 'Questions usually contain a question mark. ;-)';
                            return;
                        }
                        this.answer = 'Thinking...';
                        var vm = this;
                        axios.get('https://yesno.wtf/api')
                            .then(function (response) {
                                vm.answer = _.capitalize(response.data.answer);
                            })
                            .catch(function (error) {
                                vm.answer = 'Error! Could not reach the API. ' + error;
                            })
                    },
                    // 这是我们为用户停止输入等待的毫秒数
                    500
                )
            }
        })
    </script>
</body>


</html>